Study of the heterogeneous reaction of O3 with CH3SCH3 using the wetted-wall flowtube technique

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Study of the heterogeneous reaction of O3 with

CH3SCH3 using the wetted-wall flowtube technique

M. Barcellos da Rosa, W. Behnke, C. Zetzsch

To cite this version:

M. Barcellos da Rosa, W. Behnke, C. Zetzsch. Study of the heterogeneous reaction of O3 with CH3SCH3 using the wetted-wall flowtube technique. Atmospheric Chemistry and Physics Discussions, European Geosciences Union, 2003, 3 (2), pp.1949-1971. �hal-00301018�

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3, 1949–1971, 2003 Study of the heterogeneous reaction of O₃with CH₃SCH₃ M. Barcellos da Rosa et al. Title Page Abstract Introduction Conclusions References Tables Figures J I J I Back Close

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Atmos. Chem. Phys. Discuss., 3, 1949–1971, 2003 www.atmos-chem-phys.org/acpd/3/1949/

c

European Geosciences Union 2003

Atmospheric Chemistry and Physics Discussions

Study of the heterogeneous reaction of O

₃

with CH

₃

SCH

₃

using the wetted-wall

flowtube technique

M. Barcellos da Rosa, W. Behnke, and C. Zetzsch

Fraunhofer-Institut f ¨ur Toxikologie und Experimentelle Medizin Nikolai-Fuchs-Str. 1, 30625 Hannover, Germany

Received: 6 February 2003 – Accepted: 21 March 2003 – Published: 14 April 2003 Correspondence to: C. Zetzsch (zetzsch@item.fraunhofer.de)

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Abstract

This work presents the heterogeneous kinetics of the reaction of CH₃SCH₃(dimethyl sulphide, DMS) with O₃(ozone) in aqueous solution at different ionic strengths (0, 0.1 and 1.0 M NaCl) using the wetted-wall flowtube (WWFT) technique. Henry’s law coe ffi-cients of DMS were determined on pure water and on different concentrations of NaCl 5

(0.1 M–4.0 M) in the WWFT from UV spectrophotometric measurements of DMS in the gas phase using a numerical transport model of phase exchange to be H (M atm−1)= 2.16±0.5 at 274.4 K, 1.47±0.3 at 283.4 K, 0.72±0.2 at 291 K, 0.57±0.1 at 303.4 K and 0.33±0.1 at 313.4 K on water, on 1.0 M NaCl to be H= 1.57±0.4 at 275.7 K, 0.8±0.2 at 291 K and on 4.0 M NaCl to be H = 0.44±0.1 at 275.7 K and 0.16±0.04 at 291 K, 10

showing a significant effect of ionic strength, µ, on the solubility of DMS according to the equation ln H= −4061 T−1 + 0.052 µ2+ 50.9 µ T−1 + 14.0. At concentrations of DMS_(liq)above 50 µM, UV spectrophotometry of both O_3(gas)and DMS_(gas)enables us to observe simultaneously the reactive uptake of O₃on DMS solution and the gas-liquid equilibration of DMS along the flowtube. The uptake coefficient, γ, of O₃ on aqueous 15

solutions of DMS, varying between 1 and 15 · 10−6, showed a square root-dependence on the aqueous DMS concentration (as expected for diffusive penetration into the sur-face film, where the reaction takes place in aqueous solution). It was smaller on NaCl solution in accord with the lower solubility of O₃. The heterogeneous reaction of O_3(gas) with DMS_(liq) was evaluated from the observations of the second order rate constant 20

(kII) for the homogeneous aqueous reaction O_3(liq)+ DMS_(liq)using a numerical model of radial diffusion and reactive penetration and leading to kII (in units of 108M−1 s−1) = 4.1±1.2 at 291.0 K, 2.15±0.65 at 283.4 K and 1.8±0.5 at 274.4 K. Aside from the expected influence on solubility and aqueous-phase diffusion coefficient of both gases there was no significant effect of ionic strength on kII, that was determined for 0.1 M 25

NaCl, leading to kII (108M−1s−1)= 3.2±1.0 at 288 K, 1.7±0.5 at 282 K and 1.3±0.4 at 276 K, and for 1.0 M NaCl, leading to 3.2±1.0 at 288 K, 1.3±0.4 at 282 K and 1.2±0.4 at 276 K, where the error limits include uncertainties of Henry’s law constants and

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fusion coefficients for DMS and O₃.

1. Introduction

The atmospheric oxidation of dimethyl sulphide (DMS) plays an important role in nature considering the climatic consequences of the cloud-forming products of this oxidation for the global radiation budget with a large contribution of heterogeneous reactions in 5

the lower atmosphere and also in terms of acid deposition, formation of marine aerosol and in the Earth’s energy balance (Charlson et al., 1987; Chin et al., 1996; Neubauer et al., 1996; Sciare et al., 2000). The dynamics of the ocean mixed- layer is known to influence sea-to-air exchange of DMS at high latitudes, and seawater concentra-tions and the vertical distribution of DMS are required to distinguish the impact of the 10

heterogeneous chemistry from meteorological effects (Jodwalis et al., 2000).

In addition, the interaction between sulphur and halogen chemistry has been dis-cussed in recent work, where DMS has been found to react with the BrO radical, indicating that BrO could be another important sink for DMS in the marine atmo-sphere, forming readily soluble dimethyl sulphoxide (DMSO) by the reaction cycle: 15

BrO+ (CH₃)₂S → Br+ (CH₃)₂SO and Br+ O₃→ BrO+ O2. This cycle corresponds

to the net reaction (CH₃)₂S+ O₃→ (CH₃)₂SO+ O₂, destroying ozone and recycling BrO to Br (see Toumi, 1994; Bedjanian et al., 1996; Ingham et al., 1999; von Glasow, 2001). The tropospheric reaction DMS + Cl has been also discussed (Chen et al., 2000), however the contribution of this reaction to the atmospheric oxidation of DMS 20

is not clear because the model calculations show a very small difference between the contribution of this reaction in comparison with the reaction BrO+ DMS → Br + DMSO (von Glasow et al., 2002). Another link of the chemistry between sulphur and halo-gen has been also suggested in terms of DMS reaction with HOCl and HOBr in the production of sulphate in the sea-salt aerosol (Vogt et al., 1996).

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As pointed out by Gershenzon et al. 2001, comparing the gas-phase reactions OH + DMS (k ∼ 2.6 · 109

M−1 s−1, Atkinson et al. 1997) and NO₃ + DMS (k = 8.5 · 108 1951

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M−1 s−1, Atkinson et al. 1997) with O₃ + DMS (k ∼ 5.0 · 102 M−1 s−1, Atkinson et al. 1997), the latter gas-phase reaction is by far too slow to be atmospherically sig-nificant. The same reaction O₃ + DMS is extremely fast in the aqueous phase, 3 to 7 · 108M−1 s−1(Lee and Zhou, 1994; Gershenzon et al. 2001), leading to DMSO as a first stable intermediate. Studies on the oxidation of DMS in the troposphere (Barone 5

et al., 1996) suggested that the combination of the reactions OH+ DMS and NO₃ + DMS can be predominating channels for the consumption of DMS in the atmosphere, in agreement with recent work (Falbe-Hansen et al., 2000), that suggests the reactions DMSO+ Cl and DMSO + NO₃ to be important as well, but typical mixing ratios and the obtained rate constants indicate that the reaction with OH should be at least two 10

orders of magnitude faster than with NO₃ or Cl. The formation of methanesulphonic acid (MSA) in the coastal Antarctic boundary layer due to the oxidation of DMS by OH has been measured (Jefferson et al., 1998), showing that MSA is formed in an atmo-spheric buffer layer above the boundary layer, followed by condensation of gas phase MSA on aerosols and transport back to the boundary layer. Heterogeneous aqueous-15

phase reactions of DMSO, CH₃SO₂H (MSIA) and MSA contribute to the oxidation of DMS and decrease the yield of SO₂, that is the relatively long-lived gaseous precursor of H₂SO₄ in the marine boundary layer and increases the yield of non-sea-salt sul-phate, nss − SO=₄ (Campolongo et al., 1999). The kinetics and mechanism of DMSO+ OH (k = 4.5 · 109M−1s−1) in aqueous phase have been recently discussed (Bardouki 20

et al., 2002), indicating that this reaction of DMSO could also influence the particle growth processes. DMSO is therefore an important but indirect source of nss − SO=₄ in the marine atmosphere through heterogeneous processes, as is proposed by different authors (Koga and Tanaka, 1993; Barnes et al., 1994). The present study reinvesti-gates Henry’s law coefficient and the heterogeneous reaction of DMS with ozone by 25

employing the wetted-wall flowtube technique and experimental conditions relevant to marine boundary layer (low temperature and high salinity).

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2. Experimental and data evaluation

DMS (99+%) and NaCl (99+%) Aldrich were used as received. NO_x− free O₃ was produced by photolysis of O₂in purified air at 185 nm by a mercury low-pressure lamp (Penray). The solutions were prepared in bidistilled water made of deionized water. The concentrations of O₃and DMS in aqueous and gas phase were obtained using the 5

reference data (aqueous molar absorptivities and gaseous absorption cross-sections) given in Table 1. The concentration of gaseous O₃was determined from UV spectra by a Kontron Uvikon 860 spectrophotometer or by a Dasibi O₃-analyzer/generator (model 1009-CP, employing UV absorption at the 254 nm Hg line). A noise limit/analytical error of 2 ppb was estimated for the Dasibi analyser. Both concentrations of DMS, 10

in aqueous and gaseous phase, were obtained by the Uvikon 860 spectrometer at a resolution of 2 nm in quartz cells at l = 1 cm (liquid sample of 1mM stock solutions, diluted for the kinetic experiments) and l = 10 cm (gas phase, flow conditions), λ = 200 − 320 nm.

2.1. Henry’s law coefficient of DMS 15

The Henry’s law coefficient of DMS was determined from the equilibration of DMS_(gas) with water and various aqueous solutions of NaCl (0.1, 1 and 4 M) at several temper-atures and contact times with the liquid film in the WWFT, as shown in Fig. 1 (curve A) at 274.4 K for water (where 400 ml of a 1 mM stock solution of DMS in a bubbler served as reservoir of DMS_(gas), passing the air through this solution directly into the 20

WWFT). The flowtube was made of Duran glass and had an inner diameter of 0.6 cm with a movable inlet (by 140 cm) to vary the contact time. The movable gas inlet and outlet of the flowtube were made of PTFE tubing (outer diameter 0.6 cm, inner diameter 0.4 cm). A valve at the exit of the bubbler could be switched to alternatively monitor the level of DMS_(gas) at the inlet or at the outlet of the WWFT connected by Teflon tubing 25

to a 10 cm absorption cell in the spectrophotometer to observe the concentrations of DMS involved in the equilibrium DMS_(gas)_DMS_(aq) from the spectra. Using an air

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flow of 70 ml/min and an aqueous flow of 3 ml/min the measurements were started af-ter an equilibration time of at least 10 min. Then the absorption of DMS was monitored in the outflow of the WWFT at contact lengths up to 140 cm (varied every 6 min each), alternatively monitoring the corresponding absorption of DMS in the inflow each 6 min in the meantime (allowing 3 min for the equilibration each). Since the inflow level of 5

DMS was observed to decrease exponentially with a lifetime of about 1 h, the values corresponding to the WWFT measurements were interpolated accordingly. Absorption spectra of the outflow and the inflow are shown in the inset of Fig. 1 (curves B). The interpolated consumption (circles in Fig. 1A) and a numerical model calculation de-scribing the radial diffusive exchange of DMS between the gas-phase and the aqueous 10

film using the software package FACSIMILE (AEA Technology, 1994; dashed curve) are included for comparison.

2.2. Heterogeneous kinetics

The WWFT technique, described in detail by Danckwerts, 1970, was used to deter-mine the uptake coefficient, γ (the fraction of gas/liquid collisions that are effective 15

in the uptake and/or chemical transformation; Hanson, 1997; Katrib et al., 2001), thus simulating chemical heterogeneous processes of the atmosphere experimentally in the laboratory, as discussed in detail in our previous work (Behnke et al., 1997, Frenzel et al., 1998). The heterogeneous aqueous-phase reaction of O_3(gas) with DMS_(aq) was studied by measuring the uptake of O_3(gas)on various concentrations of DMS_(aq) at dif-20

ferent temperatures. The loss of O₃ in air (flow ∼70 ml/min) was measured along the vertically aligned WWFT, the walls of which were conferred by a film of slowly flowing solutions of DMS (flow rate ∼3.0 ml min−1). The aqueous flow was controlled by a peri-staltic pump and was adjusted to match the linear flow velocity of the gas. In the initial runs the pump caused a major loss of 80% of the DMS from the solution by its sili-25

cone rubber tubing until replacement by tygon tubing, that was found to be permeation resistant enough. As shown in Fig. 2, the data analysis can be approximated by the as-sumption that the uptake rate is first order with respect to the gas phase concentration

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of the reacting species, i.e.

C/C₀= exp[−k_gast], (1)

where C₀and C are the concentrations at the entrance and outlet of the flow tube re-spectively, t is the average gas contact time and k_gasis the first-order loss rate constant from the gas to the liquid phase. For small uptake coefficients, the rate constant k_gas, 5

obtained from such a semilogarithmic plot is correlated to the uptake coefficient γ using the plug flow assumption (that is appropriate here because of the adjusted velocity of the film surface):

k_gas= γ· < c > /2r_tube, (2)

where < c > is the average molecular speed of the gas and r_tubeis the flowtube radius 10

(r_tube = 3.0 mm). The thickness of the aqueous film is less than 0.1 mm under our experimental conditions (Danckwerts, 1970). The molecular transport gas → liquid involves gas-phase diffusion and mass accommodation (α, the fraction of collisions with the surface that can lead to incorporation into the bulk liquid; Hanson, 1997) and the Henry’s law coefficient (Herrmann et al., 2000). In this work it is considered that 15

α γ, due the low uptake coefficient of O3(γ= (1 − 15) · 10 −6

) measured on the liquid film of DMS.

The uptake coefficient, γ, of O₃for reactive penetration into the liquid depends on the solubility of the gas, i.e. Henry’s law constant, H, the temperature, T , and the diffusion coefficient of O₃, D_aq, in aqueous phase. It is given by the equation

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γ= moelcules absorbed by the liquid layer molecules colliding with the liquid layer =

4 HRT(k1D_aq)1/2

< c > , (3)

where < c >= (8 RT/π M)1/2 and k1 is the first-order loss rate constant of O₃ in the aqueous phase.

Figure 2 shows the uptake of O₃ (monitored by the Dasibi gas analyser) on various solutions of DMS at 274.4 K. The points represent the experimental measurements and 25

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the lines the results from a numerical model calculation (see below). For the Henry’s law coefficient and the diffusion coefficient of O_3(aq)the following data given by Kosak-Channing and Helz (1983) H = 1.1 · 10−2exp[(2300 K) · (1/T − 1/T₀)] M atm−1(where T₀= 298 K) and the dependence on ionic strength, µ, is given by the equation

ln(H/M atm−1)= −2297T−1+ 2.659µ + 688.0µT−1+ 12.19 (4) 5

and D_aq = 2.0 · 10−2exp(−2200 K/T) cm2s−1given by Gershenzon et al. (2001) were used. The loss rate constant in the solution, kI, depends on the concentration of the dissolved DMS, [DMS], according to the equation

kI = kII· [DMS], (5)

where kII is the rate constant for the aqueous-phase reaction 10

O₃+ DMS → DMSO + O₂. (R1)

For an improved interpretation of our data, we simulated the observed concentrations in the flowtube by a numerical model, described by Behnke et al., 1997. The one dimensional model (cylindrical coordinates), written in the FACSIMILE language (AEA Technology, 1994), includes radial diffusion in the gas and liquid phase and chemical 15

reactions in the liquid phase. Axial diffusion is neglected, axial transport is described by progress in time. The lines in Fig. 2 from the model calculation are almost straight lines since there was a sufficient surplus of DMS over O₃in these runs with the ozone analyser. The strength of the model calculation is that it can serve also for cases with lower ratios of [DMS]/[O₃] like those displayed in Fig. 3, where DMS is consumed 20

almost completely. At high concentrations of DMS (> 50µM) it is possible to determine simultaneously the fast reaction that occurs in the surface of the liquid between O₃and DMS and the liquid-gas equilibration of DMS (Henry’s law coefficient) along the flow tube reactor by monitoring the spectra of both O₃ (Fig. 3 curves A) and DMS (Fig. 3, curves B) by the UV spectrophotometer.

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3. Results and discussion

3.1. Henry’s law coefficient of DMS

The Henry’s law coefficient of DMS on pure water was determined to be (in units of M atm−1) H= 2.16±0.5 at 274.4 K, 0.72±0.2 at 291 K and 0.33±0.1 at 313.4 K; on 1.0 M NaCl we found H= 1.57±0.4 at 275.7 K and 0.80±0.05 at 313 K, and on 4.0 M NaCl H 5

= 0.44±0.1 at 275.7 K and 0.16±0.04 at 291 K. These data are presented in Fig. 4 in comparison with literature data. The Henry’s law coefficient of DMS was determined at different concentrations of NaCl, due to fact that NaCl is the major component of seasalt aerosol ([Cl−]= 550 mM in seawater; Jaenicke, 1988), and also due to the importance of NaCl on a global scale (contributing about 60% of the natural sources of aerosol 10

particles and more than 40%–60% to the natural aerosol mass, Pruppacher and Klett, 1997). The quantification of the Henry’s law coefficient of DMS on high concentrations of NaCl (4.0 M NaCl) is of interest, considering that aerosols are usually solutions with molalities of NaCl ≥ 10 Mol/kg, therefore presenting very high ionic strengths (Tang, 1997). Our data on Henry’s law coefficient can be described by Eq. (6):

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ln H= a · T−1+ b · µ2+ c · µ · T−1+ d (7)

with the parameters: a = −4061 ± 318; b = 0.052 ± 0.030; c = 50.9 ± 27.0 and d = 14.0±1.1, where introducing a linear term b·µ instead of b·µ2did not significantly improve the quality of the fit. Our data are much lower than the value of Lovelock et al. and about 30% higher than those of Hine and Weimar, Przyani et al., Dacey et al., 20

and de Bruyn et al., confirming the dependence on molality observed by Dacey et al. (1984) and de Bruyn et al. (1995) and confirming the temperature dependence of the literature data. Due to the difficulties of handling the DMS solutions and determining the gaseous DMS levels (reference and after exposure to the water film) in an absorption cell connected via 2 m of Teflon tubing and the short wavelength of 202 nm employed 25

for the detection of DMS (close to the short wavelength limit of the spectrophotometer, see Alebic-Juretic et al., 1991) this agreement with literature data must be considered

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as satisfactory.

3.2. Kinetic measurements

The rate constants determined by the WWFT in the present study are summarized in Table 2 in comparison with literature data. Figure 5 shows a compilation of all rate constants kII obtained in this work for the reaction of O₃ with DMS in pure water in 5

comparison with literature data and the respective temperature dependence. It should be noted that our model calculation neglects the axial diffusion in the gas phase that may become significant at the steep gradients at the very beginning of gas contact with the liquid film in the tube. Furthermore, our data in NaCl solution are lower than those in pure water, and this may partly be caused by an experimental problem with the smaller 10

excess of DMS of those measurements. Another point is, that in our initial evaluation of the measurements on NaCl solutions our data at 1 M NaCl were about 10% lower than displayed in Fig. 5. Then we considered the slightly lower diffusion coefficients of the reactants in the saline solutions, known to be inversely proportional to the viscosity. At 20◦C the viscosity of a 1 M NaCl solution is 9.5% higher than that of pure water (CRC 15

Handbook, 1982), and the influence of salinity of seawater on viscosity is known to be slightly smaller at lower temperature (D’Ans-Lax, 1967). Considering this influence of a lower diffusion coefficient in 1M NaCl as compared to 0.1 M corrected the rate constants correspondingly upwards and brought the two series with NaCl into much better agreement. The measurements in pure water were obtained with a lower level 20

of O₃ using an ozone analyser for detection and may thus represent more favourable conditions for the kinetic evaluation. Taking our data altogether we obtain an Arrhenius activation energy similar to that determined by Lee and Zhou (1994).

Our attempts to determine the rate constant directly in solution by the stopped flow method turned out to be unsuccessful (similar to a statement in the paper by Lee and 25

Zhou), the reaction being too rapid to monitor the decay of O₃ in the presence of a surplus of DMS required for pseudo-first-order evaluation. With approximately equal concentrations of DMS and O₃ around 5 µM the absorption of ozone after a

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time for mixing of about 1 ms disappeared with a lifetime of about 5 ms at 275 K. This corresponds to about 0.5·108M−1s−1and confirms the rapid reaction in homogeneous aqueous solution.

Considering the slightly larger solubility of DMS obtained from the gas-phase obser-vations of our study might indicate an underestimated loss of DMS from our system 5

(by permeation, e.g.). Such an underestimated loss would decrease the observed rate constants slightly.

According to Gershenzon et al. (2001), the mechanism of the heterogeneous aqueous-phase reaction of O₃ with DMS can be interpreted mainly in terms of two complementary chemical factors: the chemical attack of the nucleophilic S on the elec-10

trophile O₃ and the participation of the solvent (acting as a polar adduct), facilitating the formation of DMSO. In contrast to DMS, DMSO [(CH₃)₂S+− O−] presents a po-larised S-O bond, where DMSO acts (or is attacked) as an O-based nucleophile (or an S-based electrophile respectively), depending of course on the reaction partner.

4. Atmospheric implications

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The chemistry and the transport/equilibration of DMS from gas to liquid phase repre-sent an interesting subject for the understanding of the tropospheric heterogeneous reactions involving the aqueous phase, considering that the kinetics O₃+ DMS can be seen as a key reaction in comparison with other reactants, such as the radicals NO₃, OH, BrO and Cl, since it is an exceptionally fast aqueous-phase reaction and almost 20

the only night-time sink of ozone in the chemistry of the remote marine boundary layer. In that respect DMS is expected to compete with bromide in the reaction of sea-spray with gaseous ozone as an antagonist of halogen activation in the aqueous phase. In the last 10 years, the high reactivity of halogens in the atmosphere has been studied with respect to their role in the well-known “ozone hole” where the interactions between 25

gas and particulate phase and heterogeneous chemistry become important (Brasseur et al., 1999). On the other hand, DMS may act as a promoter of halogen activation in

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the gas-phase by supporting the recycling of BrO to the more ozone-reactive Br. About the importance of the Henry’s law coefficient for the troposphere, this coeffi-cient is in direct connection with the study of the equilibria of species in terms of the cloud chemistry and aerosol formation at high salt concentrations. The laboratory sim-ulation of the transport and reaction of a molecule such as DMS in aqueous phase is 5

the first step for an understanding of the possible chemical and physical effects on this heterogeneous system and why enormous annual variations of the concentration of DMS are observed on the marine surface.

5. Conclusions

The correct understanding and simulation of the tropospheric heterogeneous aqueous-10

phase reactions and of the molecular gas/ liquid equilibrium (Henry’s law quantification) are fundamentals for the use in global model calculations and for atmospheric chem-istry. The heterogeneous aqueous phase reaction of O₃with DMS is considered as an exception, because the gas phase reactions are normally fast compared to the same reaction in aqueous phase. As observed in this work and in agreement with previous 15

work (Lee and Zhou, 1994; Gershenzon et al., 2001), the reaction of O₃ with DMS in aqueous phase is shown to be a factor of about one million faster than in gas phase, motivating this experimental study. We suppose that the heterogeneous reaction may interfere in the determination of gaseous DMSO in field measurements by denuders at high ozone levels and suggest that it constitutes a significant night-time sink of DMS, 20

producing DMSO in the marine atmosphere where DMSO is further oxidised to H₂SO₄. Another aspect of this work is that the experimental set-up and concept presented are completely different from others work (-bubbler-type gas-liquid reactor (Lee and Zhou, 1994) and horizontal bubble train apparatus (Gershenzon et al., 2001)), sup-plementing in this case the understanding of an important tropospheric reaction with 25

this complementary and versatile technique (WWFT). A quantification of the Henry’s law coefficient is also useful because of its impact (Crutzen and Lawrence, 2000) on

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precipitation scavenging during the transport of trace gases and implications on the meteorology and global changes.

Acknowledgement. This study was supported by the EU within project EL-CID

(EVK2-CT-1999-00033). Furthermore, M. Barcellos da Rosa wishes to thank H.-U. Kr ¨uger for valuable support and the DAAD for a stipend.

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References

Adewuyi, Y. G. and Carmichael, G. R.: Kinetics of oxidation of dimethyl sulfide by hydrogen peroxide in acidic and alkaline medium, Environ. Sci. Technol., 20, 1017–1022, 1986. AEA Technology: FACSIMILE version 3.0, AEA Technology, Harwell, Didcot, Oxfordshire, OX11

ORA, UK, 1994. 10

Alebic-Juretic, A., G ¨usten, H., and Zetzsch, C.: Absorption spectra of hexachlorobenzene ad-sorbed on SiO₂powders, Fresenius J. Anal. Chem. 340, 380–383, 1991.

Amels, P., Elias, H., and Wannowius, K. J.: Kinetics and mechanism of the oxidation of dimethyl sulfide by hydroperoxides in aqueous medium. J. Chem. Soc. Faraday Trans., 93, 2537– 2544, 1997.

15

Atkinson, A. Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, J. A., and Rossi, M. J.: Evalu-ated kinetic, photochemical and heterogeneous data for atmospheric chemistry: Supplement VI, J. Phys. Chem. Ref. Data, 26, 1329–1499, 1997.

Bandy, A. R., Thornton, D. C., Blomquist, B. W., Chen, S., Wade, T. P., Ianni, J. C., Mitchell, G. M., and Nadler, W.: Chemistry of dimethyl sulfide in the equatorial pacific atmosphere, 20

Geophys. Res. Letters, 23, 7441–7444, 1996.

Bardouki, H., Barcellos da Rosa, M., Mihalopoulos, N., Palm, W.-U., and Zetzsch, C.: Kinetics and mechanism of the oxidation of dimethylsulfoxide (DMSO) and methanesulphinate (MSI−) by OH radicals in aqueous medium, Atmos. Environ., 36, 4627–4634, 2002.

Barnes, I., Becker, K. H., and Patroescu, I.: The tropospheric oxidation of dimethyl sulfide: A 25

new source of carbonyl sulfide, Geophys. Res. Letters, 21, 2389–2392, 1994.

Barone, S. B., Turnipseed, A. A., and Ravishankara, A. R.: Reaction of OH with dimethyl sulfide (DMS), 1. Equilibrium constant for OH+ DMS reaction and the kinetics of the OH.DMS + O₂ reaction, J. Phys. Chem., 100, 14 694–14 702, 1996.

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Bedjanian, Y., Poulet, G., and Le Bras, G.: Kinetic study of the reaction of BrO radicals with dimethylsulphide, Intern. J. Chem. Kinetics, 28, 383–389, 1996.

Behnke, W., George, C., Scheer, V., and Zetzsch, C.: Production and decay of CINO2from

the reaction of gaseous N₂O₅with NaCl solution: Bulk and aerosol experiments, J. Geophys. Res. D., 102, 3795–3804, 1997.

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Brasseur, G. P., Orlando, J. J., and Tyndall, G. S. (eds.): Atmospheric chemistry and global change, Oxford University Press, New York, Oxford, 1999.

Campolongo, F., Saltelli, A., Jensen, N. R., Wilson, J., and Hjorth, J.: The role of multiphase chemistry in the oxidation of dimethylsulphide (DMS), J. Atmos. Chem., 32, 327–356, 1999. Charlson , R. J., Lovelock, J. E., Andreae, M. O., and Warren, S. G.: Oceanic phytoplankton, 10

atmospheric sulphur, cloud albedo and climate, Nature, 326, 655–661, 1987.

Chen, G., Davis, D. D., Kasibhatla, A. R., Bandy, D. C., Thornton, B. J., Huebert, A. D., Clarke, and Blomquist, B. W.: A study of DMS oxidation in the Tropics: Comparison of Christmas Island field observations of DMS, SO₂, and DMSO with model simulations. J. Atmos. Chem., 37, 137–160, 2000.

15

Chin, M., Jacob, D. J., Gardner, G. M., Foreman-Fowler, M. S., and Spiro, P. A.: A global three-dimensional model of tropospheric sulfate, J. Geophys. Res. D., 101, 18 667–18 690, 1996.

CRC Handbook on Physics and Chemistry (ed. R.C. Weast): 62nd edition, Boca Raton (FL), USA, 1981–1982.

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Crutzen, P. J. and Lawrence, M. G.: The impact of precipitation scavenging on the transport of trace gases: A 3-dimensional model sensitivity study, J. Atmos. Chem., 37, 81–112, 2000. Dacey, J. W. H., Wakeham, S. G., and Howes, B. L.: Henry’s law constants for dimethylsulfide

in freshwater and seawater, Geophys. Res. Letters, 11, 991–994, 1984.

Danckwerts, P.: Gas-liquid reactions, Chemical Engineering series, Mc-Graw Hill, New York, 25

1970.

D’Ans-Lax: Taschenbuch f ¨ur Chemiker und Physiker, 3rd edition, Vol. I (eds. E. Lax and C. Synowietz), Springer, Heidelberg, 1967.

de Bruyn, W. J., Swartz, E., Hu, J. H., Shorter, J. A., and Davidovits, P.: Henry’s law solubilities and Setchenow coefficients for biogenic reduced sulfur species obtained from gas-liquid 30

uptake measurements, J. Geophys. Res. D., 100, 7245–7251, 1995.

Frenzel, A.: Eigenschaften und Gas-L ¨osungen-Reaktionen von Nitrylbromid, PhD Thesis, Uni-versit ¨at Hannover, 1997.

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Frenzel, A., Scheer, W., Sikorski, R., George, C., Behnke, W., and Zetzsch, C.: Heterogeneous interconversion reactions of BrNO₂, ClNO₂, Br₂and Cl₂, J. Phys. Chem. D., 102, 1329–1337, 1998.

Gershenzon, M., Davidovits, P., Jayne, J. T., Kolb, C. E., and Worsnop, D. R.: Simultaneous uptake of DMS and O₃on water, J. Phys. Chem., 105, 7031–7036, 2001.

5

Hanson, D. R.: Surface-specific reactions on liquids, J. Phys. Chem. B, 101, 4998–5001, 1997. Hearn, C. H., Turcu, E., and Joens, J. A., The near U.V. absorption spectra of dimethyl sulfide,

diethyl sulfide and dimethyl disulfide at T = 300 K, Atmos. Environ., 24A, 1939–1944, 1990. Herrmann, H., Ervens, B., Jacobi, H. -W., Wolke, R., Nowacki, P., and Zellner, R.: CAPRAM

2.3: A chemical aqueous phase radical mechanism for tropospheric chemistry, J. Atmos. 10

Chem., 36, 231–284, 2000.

Hine, J., and Weimar, R. D.: Carbon basicity, J. Amer. Chem. Soc., 87, 3387–3396, 1965. Ingham, T., Bauer, D., Sander, R., Crutzen, P. J., and Crowley, J. N.: Kinetics and products

of the reactions BrO+ DMS and Br + DMS at 298 K, J. Phys. Chem. A., 103, 7199–7209, 1999.

15

Jaenicke, R.: Aerosol physics and chemistry, in Landolt-B ¨ornstein: Zahlenerte und Funktionen aus Naturwissenschaften und Technik, Vol. 4b, Springer, 1988.

Jefferson, A., Tanner, D. J., Eisele, F. L., Davis, D. D., Chen, G., Crawford, J., Huey, J. W., Torres, A. L., and Berresheim, H.: OH photochemistry and methane sulfonic acid formation in the coastal Antarctic boundary layer, J. Geophys. Res. D., 103, 1647–1656, 1998. 20

Jodwalis, C. M., Benner, R. L., and Eslinger, D. L.: Modelling of dimethyl sulfide ocean mixing, biological production, and sea-to-air flux for high latitudes, J. Geophys. Res. D., 105, 14387– 14399, 2000.

Katrib, Y., Deiber, G., Schweitzer, F., Mirabel, P., and George, C.: Chemical transformation of bromine chloride at the air/water interface, J. Aerosol Sci. 32, 893–911, 2001.

25

Kosak-Channing, L. F. and Helz, G.: Solubility of ozone in aqueous solution of 0-0.6 M ionic strength, Environ. Sci. Technol. 17, 145–149, 1983.

Koga, S. and Tanaka, H.: Numerical study of the oxidation process of dimethylsulfide in the marine atmosphere, J. Atmos. Chem., 17, 201–228, 1993.

Lee, Y. N. and Zhou, X.: Aqueous reactions kinetics of ozone and dimethyl sulfide and its 30

atmospheric implications, J. Geophys. Res. D., 99, 3597–3605, 1994.

Lovelock, J. E., Maggs, R. J., and Rasmussen, R. A.: Atmospheric dimethylsulfide and the natural sulfur cycle, Nature, 237, 452–453, 1972.

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Neubauer, K. R., Sum, S. T., Johnston, M. V., and Wexler, A. S.: Sulfur speciation in individual aerosol particles, J. Geophys. Res. D., 101, 18 701–18 707, 1996.

Pruppacher, H. R. and Klett, J. D.: Microphysics of clouds and precipitation, Kluwer Academic Pub., London, 1997.

Przyjazny, A., Janicki, W., Chrzanowski, W., and Staszewski, R.: Headspace gas chro-5

matografic determination of distribution coefficients of selected organosulfur compounds and their dependence on some parameters, J. Chromatography, 280, 249–260, 1983.

Sander, R.: Compilation of Henry’s law constants for inorganic and organic species of potential importance in environmental chemistry,http://www.mpch-mainz.mpg.de/∼_{sander/res/henry.} html.

10

Sciare, J., Mihalopoulos, N., and Dentener, F. J.: Interannual variability of atmospheric dimethyl-sulfide in the Southern Indian Ocean, J. Geophys. Res. D., D105, 26369–26377, 2000. Schwartz, S. E.: Mass transport considerations pertinent to aqueous phase reactions of gases

in liquid water clouds, in W. Jaeschke (ed.), Chemistry of Multiphase Atmospheric Systems, NATO ASI Series, Vol. 6, Springer, Berlin, 415–471, 1986.

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Tang, I. N.: Thermodynamic and optical properties of mixed-salt aerosols of atmospheric inter-est, J. Geophys. Res. D., 102, 1883–1893, 1997.

Toumi, R.: BrO as a sink for dimethylsulphide in the marine atmosphere, Geophys. Res. Letters, 21, 117–120, 1994.

Vogt, R., Crutzen, P. J., and Sander, R.: A mechanism for halogen release from sea-salt aerosol 20

in the remote marine boundary layer, Nature, 383, 327–330, 1996.

von Glasow, R.: Modeling the gas and aqueous phase chemistry of the marine boundary layer, PhD Thesis, Universit ¨at Mainz, 2001.

von Glasow, R., Sander, R., Bott, A., and Crutzen, P.: Modeling halogen chemistry in the marine boundary layer 2. Interactions with sulfur and the cloud-covered MBL, J. Geophys. Res. D., 25

107, 4323–4336, 2002.

von Gunten, U. and Oliveras, Y.: Advanced oxidation of bromide-containing waters: bromate formation mechanisms, Environ. Sci. Technol., 32, 63–70, 1998.

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Interactive Discussion Table 1. Aqueous molar absorptivities and absorption cross section of O₃and DMS

Molecule λ/nm ε/M−1cm−1and working range

σ/cm2molecule−1 O_3(liquid) 258 3000(a) 4 − 15 µM O_3(gas) 254 1.14 · 10−17(b) (0.2 − 50) · 1014molec · cm−3 CH₃SCH_3(liquid) 205 1600(c) 0.15 − 130 µM CH3SCH3(gas) 202 1.42 · 10 −17(d ) (0.3 − 10) · 1015molec · cm−3 (a)

von Gunten and Oliveras, 1998;

(b)

Atkinson et al., 1997;

(c)

Adewuyi and Carmichael, 1986;

(d )

Hearn et al., 1990.

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Interactive Discussion Table 2. Second-order rate constants (kII) and estimated error limits∆kIIobtained in this work

in comparison with literature data

This work Lee and Zhou, 1994 Gershenzon et al., 2001 [NaCl]/M (kII±∆kII )/ T /K kII/ T /K KII/ T /K 108M−1s−1 108M−1s−1 108M−1 s−1 0 4.1± 1.2 291 6.1 298 11 300 2.15±0.65 283.4 3.3 288 8.6 293 1.8±0.5 274.4 1.9 278 5.9 283 5.1 274 0.1 3.2±1.0 288 1.7±0.5 282 – – – – 1.3±0.4 276 1.0 3.2±1.0 288 1.3±0.4 282 – – – – 1.2±0.4 276

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Print Version Interactive Discussion

t / s

0 5 10 15 20 25 30 35

[DMS]

0

/[DMS]

1 λ / nm 200 210 220 230 240 Absorbance 0.00 0.05 0.10 0.15 0.20 0.25 DMS_gas/0cm DMS/140cm

A

B

outflow

inflow (ref spectra)

interpolated consumption of DMS

numerical model calculation

Figure 1. Equilibration of DMS (gas) with water at 274.4K at several contact times (A) that correspond to gas-liquid interaction lengths of 0, 2, 4, 6, 8, 10, 15, 20, 40, 60, 80, 100, 120 and 140 cm and the absorption spectra (B) of the inflow (green dashed curves) and the outflow (blue solid curves).

Fig. 1. Equilibration of DMS (gas) with water at 274.4 K at several contact times (A) that

correspond to gas-liquid interaction lengths of 0, 2, 4, 6, 8, 10, 15, 20, 40, 60, 80, 100, 120 and 140 cm and the absorption spectra(B) of the inflow (green dashed curves) and the outflow

(blue solid curves).

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t / s

0

3

6

9

12

15 ln [O

3

]/[O

3

]

0

-4

-3

-2

-1

0 [DMS

_(aq)

]

0.19µM

1.90µM

4.75µM

9.50µM

19.0µM

274.4K

Figure 2. Exponential decay of O

3

monitored by the ozone analyser (symbols) on various

concentrations of DMS in comparison with a model calculation (curves).

Fig. 2. Exponential decay of O₃ monitored by the ozone analyser (symbols) on various con-centrations of DMS in comparison with a model calculation (curves).

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λ / nm

200

220

240

260

280

300

320 Absorbance

0.00

0.01

0.02

0.03

0.04

0.05 [O

_3(gas)

]

₀

[DMS]

₀

291K

[DMS

_(gas)

]

_140cm

h

₀

= 0 cm

A

B

Figure 3. Simultaneous spectral characterisation of the uptake of O3(gas) on DMS(liq) and the

liquid-gas equilibration of DMS along the flowtube reactor. The spectra are displayed for contact lengths of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 50, 100 and 140 cm.

Fig. 3. Simultaneous spectral characterisation of the uptake of O_3(gas)on DMS(liq)and the

liquid-gas equilibration of DMS along the flowtube reactor. The spectra are displayed for contact lengths of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 50, 100 and 140 cm.

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1000/T / K

-1

3.2

3.3

3.4

3.5

3.6

3.7 H

DMS

/ M

· atm

-1

0.1

1

4.0M NaCl (this work) 1.0M NaCl (this work) H₂O Dacey et al., 1984

Hine and Weimar, 1965 Przyjazny at al.1983 H₂O seawater Lovelock et al., 1972 seawater seawater (0.50M NaCl) H₂O this work de Bruyn et al., 1995

Figure 4. Henry’s law coefficients obtained in this work in comparison with literature data.

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1000/T / K

-1

3.3

3.4

3.5

3.6

3.7 k

II

·

10

8

/ M

-1

s

-1

1

10 Gershenzon et al., 2001

Lee and

Zhou, 1994

in H₂O in 0.1M NaCl in 1.0M NaCl

this work

Figure 5. Temperature dependence of the reaction of DMS with ozone in the aqueous phase observed in the present study (open symbols) in comparison with literature data (filled symbols) by Lee and Zhou (circles) and Gershenzon et al. (squares). Our data in pure water, 0.1M NaCl and 1.0M NaCl agree among each other within the error limits and confirm the earlier data by Lee and Zhou.

Fig. 5. Temperature dependence of the reaction of DMS with ozone in the aqueous phase

observed in the present study (open symbols) in comparison with literature data (filled symbols) by Lee and Zhou (circles) and Gershenzon et al. (squares). Our data in pure water, 0.1 M NaCl and 1.0 M NaCl agree among each other within the error limits and confirm the earlier data by Lee and Zhou.

Study of the heterogeneous reaction of O<sub>3</sub> with CH<sub>3</sub>SCH<sub>3</sub> using the wetted-wall flowtube technique

HAL Id: hal-00301018

https://hal.archives-ouvertes.fr/hal-00301018

Study of the heterogeneous reaction of O3 with

CH3SCH3 using the wetted-wall flowtube technique

M. Barcellos da Rosa, W. Behnke, C. Zetzsch

To cite this version:

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Study of the heterogeneous reaction of O

3

with CH

3

SCH

3

using the wetted-wall

flowtube technique

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/[DMS]

A

B

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t / s

0

3

6

9

12

15

ln [O

]/[O

]

-4

-3

-2

-1

0

[DMS

]

0.19µM

1.90µM

4.75µM

9.50µM

19.0µM

274.4K

Figure 2. Exponential decay of O

monitored by the ozone analyser (symbols) on various

concentrations of DMS in comparison with a model calculation (curves).

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λ / nm

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220

240

260

280

300

320

Absorbance

0.00

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